IP geolocation

IP geolocation is the process of turning an IP address into a physical location. It cannot be done with 100% accuracy, but there are a growing number of both commercial and non-commercial services that can do it pretty well.

Hostip.info is a community-based project to geolocate IP
addresses, making the database freely available (see
below) but it needs you to put in your city to make it
work. It only takes 10 seconds, and you'll get a warm
fuzzy feeling of 'doing the right thing' :-)